Well i let my car overheat pritty badly last weekend (was boiling steam from the bonnet and was 115degrees C by the time i pulled over). Consequenly i think i have blown the head gasket, the engine uses more coolant than fuel, milky oil, steam out the catch can etc. Also it hydraulic locked last time i tryed cranking it over and sounds like a 2cyl!
My question is will/could my alloy head be stuffed because of this(cracked/warped etc) or are they fairly tough?
Unfortunatelly i wont have time to get it tested and ill have to chuck a fresh gasket in and hope for the best so i can come on the S.A dyno/cruise Ill be doing it tomorrow and ill take some pics

They are known to warp/crack etc....it would be definitely worth getting checked - worst case put the new gasket and keep an eye on it.

would i be able to ckeck for warpage by using steel ruller and looking for gaps or wont that be acurate enough, might need a bigger radiator also!

yes you can check it with a big steel ruler as long as you know that the ruler is straight

just put it across the head and see if you can see day light coming through under the ruler
depending on the gap you might be able to put the head back on with just a new head gasket and some extra sealant

but i just did my head gasket on my L series yesterday and when we checked the head it wasnt really within the acceptable limit but it hadnt been using alot of water or anything

so id be saying you will most likely need to get your head straightened

The acceptable limit is up to 0.004 in. (0.1 mm). According to the Nissan factory service manual for A12. See Head Gasket

My experience with "blown" gaskets is that the head is usually OK. However yours sounds like a serious overheat, so be sure to measure the flatness.


Alloy heads are much better than cast iron. The alloy will move and let the gasket leak where iron ones are more prone to crack. At least I think that's true. Somebody correct me if I got it wrong.

well i ripped the head off the other day, as suspected it has blown between two water galleries and no. 1 cylinder. The thing that has me confused is the gasket looks to be blown out/warped, it looks oval, there is also an oval gasket mark on the block on no. 1 cyl. Here is a picture, the red mark is showing problem area!




Here is another picture showing the two blown water galleries, again circled in red




The head also looks like its got real hot down the front end near blown section of gasket, the port of cyl no one has a golden tinge to the alloy, the rest are normal.
My question is what are peoples opinions on this, can overheating do this or is it more, maybe a dud gasket? Cheers everyone

JUST LOOK what happened to mine :


http://datsun1200.com/modules/myalbum/photo.php?lid=11567

that gasket looks absolutley funked!
i must have been a bit of a cheapy and looks to have warped under the pressure/heat.

my advice: skim the head (if it is do-able), buy a good quality head gasket. wet-and-dry the top of the block and reinstall.

i'd also be wondering why it over heated so badly... was it the driver or a mechanical fault. is the thermostat working properly?

yea it was a $40 acl kit from sprints, it overheated from my own stupitity the first time (doing skids and got a litle carried away, private roads of course). The other time was when it used all the radiator fliud up from the above id assume. What brand is a good headgasket and were would i get one? For now another acl gasket will go back in so its ready for the weekend

genuine head gaskets are the go, but will cost a bit.
permaseal also make good stuff. where i worked as a mechanic they used them and never had a car come back for one...
tomei is a japanese company that makes good stuff for A series'. they still sell head gaskets.